The curing process of epoxy asphalt was analyzed by Fourier transform infrared （FT-IR） spectroscopy. Effect of curing temperature on viscosity of epoxy asphalt, and changes of mechanical properties with curing time ...The curing process of epoxy asphalt was analyzed by Fourier transform infrared （FT-IR） spectroscopy. Effect of curing temperature on viscosity of epoxy asphalt, and changes of mechanical properties with curing time were investigated. The evolution of concentration of epoxy band was followed as a function of the applied curing process.The experimental results indicate that the curing reaction rate of epoxy asphalt is invariable before 70 min at 120 ℃, and it decreases when curing time exceeds 70 min. The viscosity of epoxy asphalt increases slowly with curing time at initial curing stage. But it increases quickly after initial curing stage and the initial curing time decreases as the curing temperature increases, The tensile strength increases slowly at incipient curing stage and increases rapidly when curing time is form 20 min to 70 min. The elongation at break shows a decrease with curing time, but it exceeds 200% after cured.展开更多
By using NaOH and Na2SiO3 as the activator,the mechanical properties and shrinkage of the geopolymer after incorporation of 0%,10%,20%,and 30% epoxy resin were investigated.The mechanism of epoxy resin toughening meta...By using NaOH and Na2SiO3 as the activator,the mechanical properties and shrinkage of the geopolymer after incorporation of 0%,10%,20%,and 30% epoxy resin were investigated.The mechanism of epoxy resin toughening metakaolin based geopolymer was analyzed by X-ray diffraction,scanning electron microscopy and Fourier transform infrared spectroscopy.It was shown that with the increases of epoxy resin,the shrinkage performance was obviously improved and the flexural strength increased by 53.5%.The compressive strength of EGP10,EGP20,and EGP30 increased by 49.12%,57.04%,and 65.34% after curing for 28 days,respectively.There were five obvious vibration peaks of 811 cm^-1,1 000 cm^-1,1 050 cm^-1,1 590cm^-1,and 3 400 cm^-1 in the geopolymer and the undisturbed metakaolin.More geopolymer gels were formed in the material and the microstructure was more compact.展开更多
This paper discusses the fundamental principle of microwave heating, and based on the advantages of microwave heating, use maleic anhydride as curing agent. The technology of microwave curing E44 epoxy resins is inves...This paper discusses the fundamental principle of microwave heating, and based on the advantages of microwave heating, use maleic anhydride as curing agent. The technology of microwave curing E44 epoxy resins is investigated, the mechanical properties of cured epoxy resin samples in different contents of curing agent by microwave and thermal curing methods are measured respectively, and then some experimental results for which are obtained. At last, this paper analyses why microwave curing can improve mechanical property of epoxy resin.展开更多
Sustained casing pressure(SCP)is a crucial issue in the oil and gas production lifecycle.Epoxy resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliabl...Sustained casing pressure(SCP)is a crucial issue in the oil and gas production lifecycle.Epoxy resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliable barriers.The injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation operations.This study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid leakage.The investigation evaluated the viscosity,compressive strength,and brittleness index of the epoxy resin sealant,as well as its tangential and normal shear strengths in conjunction with casing steel.The flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in cracks.The results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin,ranging from 1.5 to 6 h,and reduced the initial viscosity from 865.53 to 118.71 m Pa,s.The mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor decrease.The epoxy resin containing 30%curing agent exhibited optimal mechanical properties.After a 14-day curing period,the epoxy resin's compressive strength reached81.37 MPa,2.12 times higher than that of cement,whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy resin.The brittleness index of epoxy resin is only 3.42,demonstrating high flexibility and toughness.The tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times,respectively.In a 0.5 mm-wide crack,the injection pressure of the epoxy resin remained below 0.075 MPa,indicating superior injection and flow capabilities.Conversely,the injection pressure of cement surged dramatically to 2.61 MPa within 5 min.The breakthrough pressure of0.5 PV epoxy resin reached 7.53 MPa,decreasing the crack's permeability to 0.02 D,a mere 9.49%of the permeability observed following cement plugging.Upon sealing a 2 mm-wide crack using epoxy resin,the maximum breakthrough pressure attained 5.47 MPa,3.48 times of cement.These results suggest that epoxy resin sealant can be employed safely and effectively to seal cracks in the cement.展开更多
It is essential to design economic and efficient tougheners to prepare high-performance epoxy resin;however,this has remained a huge challenge.Herein,an eco-friendly,low-cost,and facile-fabricated bio-based hyperbranc...It is essential to design economic and efficient tougheners to prepare high-performance epoxy resin;however,this has remained a huge challenge.Herein,an eco-friendly,low-cost,and facile-fabricated bio-based hyperbranched toughener,carboxylic acid-functionalized tannic acid(CATA),was successfully prepared and applicated to the preparation of solvent-free epoxy resins.The mechanical performance,morphology,structural characterization,and thermal characterization of toughened epoxy resin system were studied.The toughened epoxy resin system with only 1.0wt%CATA reached the highest impact strength,111%higher than the neat epoxy resin system.Notably,the tensile strength and elongation at break of toughened epoxy resin systems increased moderately with increasing CATA loading.Nonphase-separated hybrids with significant toughening effect were obtained.Additionally,the thermal stabilities of toughened epoxy resin systems decreased with increasing CATA loading.This study provides an eco-friendly,cost-effective,and facile approach for the preparation of high-performance,solvent-free epoxy resins with potential for practical applications in sealing integrated circuits and electrical devices fields.展开更多
An experimental investigation is conducted to evaluate the potential degradation in the mechanical properties of an epoxy resin and unidirectional glass fiber-reinforced epoxy (GFRE) as a result of exposure to fluctua...An experimental investigation is conducted to evaluate the potential degradation in the mechanical properties of an epoxy resin and unidirectional glass fiber-reinforced epoxy (GFRE) as a result of exposure to fluctuating temperature. A commonly used room-cured epoxy resin and the GFRE are subjected to various numbers of thermal cycles (up to 1000 heating/cooling cycles). Mechanical tests are conducted to examine the influence of thermal cycles on the stiffness, ultimate strength and strain of the resin and its GFRE. The Fourier transform-Raman spectroscopy (FT-Raman) is conducted to investigate the influence of the thermal cycles on the resulting chemical changes and curing degree of the resin. In addition, the Differential Scanning Calorimetry (DSC) analysis is conducted to investigate the variation in the glass transition temperature (Tg) of the resin as a function of the applied thermal cycles.展开更多
A high performance thermosetting epoxy resin crosslinkable at room temperature was obtained via directly moulding diglycidyl ether of bisphenol A（DGEBA） and flexibleα,ω-bisamino（n-alkylene）phenyl terminated poly...A high performance thermosetting epoxy resin crosslinkable at room temperature was obtained via directly moulding diglycidyl ether of bisphenol A（DGEBA） and flexibleα,ω-bisamino（n-alkylene）phenyl terminated poly（ethylene glycol）.The influences of the n-alkylene inserted in aminophenyl of flexible amino-terminated polythers（ATPE） on the mechanical properties,fractographs and curing kinetics of the ATPE-DGEBA cured products were studied.The results show that the insertion of n-alkylene group into the aminophenyl group of the ATPE,on one hand,can significantly increase the strain relaxation rate and decrease glass transition temperature of the ATPE-DGEBA cured products,resulting in slight decrease of the Young’s modulus and tensile strength,and significant increase of the toughness and elongation of the ATPE-DGEBA cured products.On the other hand,it can remarkably enhance the reactivity of amine with epoxy,much accelerating the curing rate of the ATPE-DGEBA systems.The activation energy of DGEBA cured by BAPTPE,BAMPTPE and BAEPTPE was 53.1,28.5 and 25.4 kJ·mol;,respectively.The as-obtained ATPE-DGEBA cured products are homogeneous, transparent,and show excellent mechanical properties including tensile strength and toughness.Thus they are promising to have important applications in structure adhesives,casting bulk materials,functional coatings,cryogenic engineering, damping and sound absorbing materials.展开更多
文摘The curing process of epoxy asphalt was analyzed by Fourier transform infrared （FT-IR） spectroscopy. Effect of curing temperature on viscosity of epoxy asphalt, and changes of mechanical properties with curing time were investigated. The evolution of concentration of epoxy band was followed as a function of the applied curing process.The experimental results indicate that the curing reaction rate of epoxy asphalt is invariable before 70 min at 120 ℃, and it decreases when curing time exceeds 70 min. The viscosity of epoxy asphalt increases slowly with curing time at initial curing stage. But it increases quickly after initial curing stage and the initial curing time decreases as the curing temperature increases, The tensile strength increases slowly at incipient curing stage and increases rapidly when curing time is form 20 min to 70 min. The elongation at break shows a decrease with curing time, but it exceeds 200% after cured.
基金the National Natural Science Foundation of China(No.51574055)。
文摘By using NaOH and Na2SiO3 as the activator,the mechanical properties and shrinkage of the geopolymer after incorporation of 0%,10%,20%,and 30% epoxy resin were investigated.The mechanism of epoxy resin toughening metakaolin based geopolymer was analyzed by X-ray diffraction,scanning electron microscopy and Fourier transform infrared spectroscopy.It was shown that with the increases of epoxy resin,the shrinkage performance was obviously improved and the flexural strength increased by 53.5%.The compressive strength of EGP10,EGP20,and EGP30 increased by 49.12%,57.04%,and 65.34% after curing for 28 days,respectively.There were five obvious vibration peaks of 811 cm^-1,1 000 cm^-1,1 050 cm^-1,1 590cm^-1,and 3 400 cm^-1 in the geopolymer and the undisturbed metakaolin.More geopolymer gels were formed in the material and the microstructure was more compact.
基金The research was supported by the open fund from the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(SKJ-9805)
文摘This paper discusses the fundamental principle of microwave heating, and based on the advantages of microwave heating, use maleic anhydride as curing agent. The technology of microwave curing E44 epoxy resins is investigated, the mechanical properties of cured epoxy resin samples in different contents of curing agent by microwave and thermal curing methods are measured respectively, and then some experimental results for which are obtained. At last, this paper analyses why microwave curing can improve mechanical property of epoxy resin.
基金funded by the National Natural Science(Grant No.52274015)。
文摘Sustained casing pressure(SCP)is a crucial issue in the oil and gas production lifecycle.Epoxy resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliable barriers.The injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation operations.This study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid leakage.The investigation evaluated the viscosity,compressive strength,and brittleness index of the epoxy resin sealant,as well as its tangential and normal shear strengths in conjunction with casing steel.The flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in cracks.The results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin,ranging from 1.5 to 6 h,and reduced the initial viscosity from 865.53 to 118.71 m Pa,s.The mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor decrease.The epoxy resin containing 30%curing agent exhibited optimal mechanical properties.After a 14-day curing period,the epoxy resin's compressive strength reached81.37 MPa,2.12 times higher than that of cement,whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy resin.The brittleness index of epoxy resin is only 3.42,demonstrating high flexibility and toughness.The tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times,respectively.In a 0.5 mm-wide crack,the injection pressure of the epoxy resin remained below 0.075 MPa,indicating superior injection and flow capabilities.Conversely,the injection pressure of cement surged dramatically to 2.61 MPa within 5 min.The breakthrough pressure of0.5 PV epoxy resin reached 7.53 MPa,decreasing the crack's permeability to 0.02 D,a mere 9.49%of the permeability observed following cement plugging.Upon sealing a 2 mm-wide crack using epoxy resin,the maximum breakthrough pressure attained 5.47 MPa,3.48 times of cement.These results suggest that epoxy resin sealant can be employed safely and effectively to seal cracks in the cement.
基金from the Special Fund for the Program for Zhejiang Provincial Natural Science Foundation of China(LZ16C160001)National Key Research and Development Program(2017YFD0601105),the National Natural Science Foundation of China(Grant No.21806142)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LY20B070002).
文摘It is essential to design economic and efficient tougheners to prepare high-performance epoxy resin;however,this has remained a huge challenge.Herein,an eco-friendly,low-cost,and facile-fabricated bio-based hyperbranched toughener,carboxylic acid-functionalized tannic acid(CATA),was successfully prepared and applicated to the preparation of solvent-free epoxy resins.The mechanical performance,morphology,structural characterization,and thermal characterization of toughened epoxy resin system were studied.The toughened epoxy resin system with only 1.0wt%CATA reached the highest impact strength,111%higher than the neat epoxy resin system.Notably,the tensile strength and elongation at break of toughened epoxy resin systems increased moderately with increasing CATA loading.Nonphase-separated hybrids with significant toughening effect were obtained.Additionally,the thermal stabilities of toughened epoxy resin systems decreased with increasing CATA loading.This study provides an eco-friendly,cost-effective,and facile approach for the preparation of high-performance,solvent-free epoxy resins with potential for practical applications in sealing integrated circuits and electrical devices fields.
文摘An experimental investigation is conducted to evaluate the potential degradation in the mechanical properties of an epoxy resin and unidirectional glass fiber-reinforced epoxy (GFRE) as a result of exposure to fluctuating temperature. A commonly used room-cured epoxy resin and the GFRE are subjected to various numbers of thermal cycles (up to 1000 heating/cooling cycles). Mechanical tests are conducted to examine the influence of thermal cycles on the stiffness, ultimate strength and strain of the resin and its GFRE. The Fourier transform-Raman spectroscopy (FT-Raman) is conducted to investigate the influence of the thermal cycles on the resulting chemical changes and curing degree of the resin. In addition, the Differential Scanning Calorimetry (DSC) analysis is conducted to investigate the variation in the glass transition temperature (Tg) of the resin as a function of the applied thermal cycles.
基金supported by the National 863 Plan(No.2006AA03A209)New Century Excellent Talent Plan (No.NECT-05-0660) from Ministry of EducationDefense Basic Research Item(No.D1420061057)
文摘A high performance thermosetting epoxy resin crosslinkable at room temperature was obtained via directly moulding diglycidyl ether of bisphenol A（DGEBA） and flexibleα,ω-bisamino（n-alkylene）phenyl terminated poly（ethylene glycol）.The influences of the n-alkylene inserted in aminophenyl of flexible amino-terminated polythers（ATPE） on the mechanical properties,fractographs and curing kinetics of the ATPE-DGEBA cured products were studied.The results show that the insertion of n-alkylene group into the aminophenyl group of the ATPE,on one hand,can significantly increase the strain relaxation rate and decrease glass transition temperature of the ATPE-DGEBA cured products,resulting in slight decrease of the Young’s modulus and tensile strength,and significant increase of the toughness and elongation of the ATPE-DGEBA cured products.On the other hand,it can remarkably enhance the reactivity of amine with epoxy,much accelerating the curing rate of the ATPE-DGEBA systems.The activation energy of DGEBA cured by BAPTPE,BAMPTPE and BAEPTPE was 53.1,28.5 and 25.4 kJ·mol;,respectively.The as-obtained ATPE-DGEBA cured products are homogeneous, transparent,and show excellent mechanical properties including tensile strength and toughness.Thus they are promising to have important applications in structure adhesives,casting bulk materials,functional coatings,cryogenic engineering, damping and sound absorbing materials.
